The 26-year-old is on the verge of leaving the Santiago Bernabeu for the Partenopei, the Italian club confirmed on Tuesday
The 26-year-old came through the youth ranks at the Santiago Bernabeu but left the club for Espanyol in 2008 before rejoining los Blancos three years later.
But he is now edging towards departing the club for a second time after failing to secure regular first team football at the club, as Rafa Benitez's Naples revolution continues.
"In the early afternoon, Jose Callejon landed in Napoli and will carry out medical examinations tomorrow morning," Napoli confirmed on the club's official Twitter page.
The former Spain Under-21 international's impending arrival could pave the way for the Partenopei to finally sanction the sale of striker Edinson Cavani.
Paris Saint-Germain has been strongly linked with the Uruguay international following coach Laurent Blanc's revelation that the Ligue 1 champion is interested in his services.